Method and system for performing a handoff in a wireless communication system, such as a hard handoff

ABSTRACT

A method for minimizing search time and disruption of current service on an originating frequency during a frequency search excursion to a target frequency as part of an inter-frequency hard handoff between cells on different RF CDMA channels. Disruption of service on the current frequency during the frequency search excursion to the target frequency is minimized by increasing the amount of power allocated to other symbols of two consecutive frames impacted by the search excursion as a function of the search excursion time. The mobile station tunes to a target frequency and collects chip samples, which are stored in a memory buffer. The mobile station returns to the originating frequency to process the collected samples.

CLAIM OF PRIORITY UNDER 35 U.S.C. §120

The present Application for Patent is a Continuation and claims priorityto patent application Ser. No. 10/634,247 entitled “METHOD AND SYSTEMFOR PERFORMING A HANDOFF IN A WIRELESS COMMUNICATION SYSTEM, SUCH AS AHARD HANDOFF” filed Aug. 4, 2003, now allowed, which is a Continuationof patent application Ser. No. 09/248,701 entitled “METHOD AND SYSTEMFOR PERFORMING A HANDOFF IN A WIRELESS COMMUNICATION SYSTEM, SUCH AS AHARD HANDOFF” filed Feb. 11, 1999, now U.S. Pat. No. 6,603,751 issuedAug. 5, 2003, which claims the benefit of Provisional Application Ser.No. 60/074,733 filed Feb. 13, 1998, all of which are assigned to theassignee hereof and hereby expressly incorporated by reference herein.

BACKGROUND

1. Field

The invention relates to wireless communication system, and, moreparticularly, to methods and apparatus for providing hard handoffsbetween cells in such systems.

2. Background

In a code division multiple access (CDMA) system, the vast majority ofhandoffs happen between cells on the same CDMA channel and use softhandoff procedures. On some occasions, the mobile stations need toperform a handoff between cells on different CDMA channels where suchchannels are at different radio frequencies (FR), often denoted asinter-frequency hard handoff. Such situations are typically, but notlimited to, either a handoff between different operators, a handoffbetween different RF channels allocated for capacity reasons, or ahandoff between different signal modulation technologies.

Before affecting an inter-frequency hard handoff, the mobile station isdirected by the base station to tune to the new target frequency,measure the radio environment (e.g., pilot signal strength of thereceived signals, etc.), and report the measurement back to the basestation. Such a procedure is specified in TIA/EIA_(—)95_B and greatlyenhances the probability of success of an inter-frequency handoff.

An essential requirement of the measurement on the target frequencyoften referred to, as “search excursion,” is to minimize the disruptionof the current service on the originating frequency. Handoffs to asecond frequency without adequate prior sampling could result in poorsignal performance. On the other hand, sampling for long periods of timemay cause the signal at the first frequency to be lost completely. Themethod described below permits the mobile station to minimize the searchtime and to limit the disruption of service.

SUMMARY

The invention overcomes the limitations described above, and providesadditional benefits by providing a method and apparatus that minimizesthe search time to another frequency and limits the disruption ofservice. This method is applicable to all types of services (voice,packet data, circuit data, signaling) the mobile station is connectedto, and does not depend on the number of dedicated code channelsassigned on the forward link and the reverse link.

One aspect of the invention involves receiving a frequency changecommand at a user station, such as a mobile station, to switch fromreceiving a signal on a first frequency to receiving a signal on atarget frequency; tuning the mobile station to the target frequency andcollecting and storing signal samples; tuning the mobile station to thefirst frequency and processing the signal samples; and transmittingsignal sample processing results to a base station.

In accordance with another embodiment of the invention, a wirelesscommunication system is disclosed herein that includes a user station,such as a mobile station, having at least a transmitter circuit, areceiver circuit, and a memory buffer. The mobile station is configuredto receive a frequency change command from a base station to switch to atarget frequency, to tune to the target frequency and collect and storesignal samples in the memory buffer, to tune back to a first frequencyand process the stored signal samples, and to transmit sample processingresults to the base station. The mobile station can be furtherconfigured to minimize the loss of forward and reverse link symbolsduring switching to the target frequency by increasing the amount ofpower allocated to the other symbols of a frame impacted by the switchto the target frequency. The additional amount of power to be allocatedto the symbols not impacted by the switch to the target frequency forthe frame to be demodulated is a function of the time the mobile stationis at the target frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures, like reference numbers identify similar elements. Forease in identifying the discussion of any particular element, the mostsignificant digit in a reference number refers to the figure number inwhich that element is first introduced (e.g., element 204 is firstintroduced and discussed with respect to FIG. 2).

FIG. 1 illustrates a typical wireless communication system that canemploy the invention.

FIG. 2 is a block diagram of typical components found in the wirelesscommunication system of FIG. 1 that can employ the invention.

FIG. 3 is a timing diagram of an inter-frequency search excursion.

FIG. 4 is a flowchart of a method for performing a frequency searchexcursion under an embodiment of the invention.

FIG. 5 is a graph of power verses time that illustrates the successionof forward link power levels related to inter-frequency searchexcursions.

FIG. 6 is a graph of power versus time that illustrates a reverse linkpower increase during search excursion.

FIG. 7 is a flowchart of a method for performing a frequency searchexcursion while minimizing disruption of service in accordance withanother embodiment of the invention.

DETAILED DESCRIPTION

A wireless communication system, and, in particular, a method andapparatus for minimizing search excursion time to a target frequency anddisruption of current service on an originating frequency is describedin detail herein. In the following description, numerous specificdetails are provided to give a thorough understanding of the invention.One skilled in the relevant technology, however, will readily recognizethat the invention can be practiced without these specific details orwith alternative elements or steps. In other instances, well-knownstructures and methods are not shown in detail to avoid obscuring theinvention.

FIG. 1 illustrates a cellular subscriber communication system 100 thatuses multiple access techniques, such as code division multiple access(CDMA) for communicating between users of user stations (e.g., mobiletelephones) and cell sites or base stations. In FIG. 1, a mobile userstation 102 communication with a base station controller 104 by means ofone or more base stations 106 a, 106 b, etc. Similarly, a fixed userstation 108 communicates with the base station controller 104, but bymeans of only one or more predetermined and proximate base stations,such as the base stations 106 a and 106 b.

The base station controller 104 is coupled to and typically includesinterface and processing circuitry for providing system control to thebase stations 106 a and 106 b. The base station controller 104 may alsobe coupled to and communicate with other base stations, and possiblyeven other base station controllers. The base station controller 104 iscoupled to a mobile switching center 110 that in turn is coupled to ahome location register 112. During registration of each user station atthe beginning of each call, the base station controller 104 and themobile switching center 110 compare registration signals received fromthe user stations to data contained in the home location register 112,as is known in the art. Handoffs may occur between the base stationcontroller 104 and other base controllers, and even between the mobileswitching center 110 and other mobile switching centers, as is known bythose skilled in this technology.

When the system 100 processes voice or data traffic calls, the basestation controller 104 establishes, maintains, and terminates thewireless link with the mobile station 102 and the fixed station 108,while the mobile switching center 110 establishes, maintains, andterminates communications with a public switched telephone network(PSTN). While the discussion below focuses on signals transmittedbetween the base station 106 a and the mobile station 102, those skilledin this technology will recognize that the discussion equally applies toother base stations and to the fixed station 108. The terms “cell” and“base station” are generally used interchangeably herein.

Referring to FIG. 2, the mobile station 10 includes an antenna 202 thattransmits signals to, and receives signals from the base station 106 a.A duplexer 203 provides a forward link channel or signal from the basestation 106 a to a mobile receiver system 204. The receiver system 204down-converts, demodulates, and decodes the received signal. Thereceiver system 204 then provides a predetermined parameter or set ofparameters to a quality measurement circuit 206. Examples of parametersmight include measured signal to noise ratio (SNR), measured receivedpower, or decoder parameters such as symbol error rate, Yamamoto metric,or parity bit check indication. A memory buffer 207 can be included foruse with the invention described herein. Additional details regardingoperation of the mobile station 102 (and the base station 106 a) arefound, for example, in U.S. Pat. No. 5,751,725, entitled “METHOD ANDAPPARATUS FOR DETERMINING THE RATE OF RECEIVED DATA IN A VARIABLE RATECOMMUNICATION SYSTEM,” assigned to the assignee of the presentinvention, and incorporated by reference herein.

The quality measurement circuit 206 receives the parameters from thereceiver system 204 and determines a quality measurement signal or powerlevel of the received signal. The quality measurement circuit 206 cangenerate energy per bit (E_(b)) or energy per symbol (E_(s))measurements from portions or windows of each frame. Preferably, theenergy per bit or energy per symbol measurements are normalized (e.g.,E_(b)/N_(o)), or normalized and include interference factors (e.g.,E_(b)/N_(t)), as is known in the art. Based on these measurements, thequality measurement circuit 206 produces a power level signal.

A power control processor 208 receives the power level signal from thequality measurement circuit 206, compares the signal to a threshold, andproduces a power control message based on the comparison. Each powercontrol message can indicate a change in power for the forward linksignal. Alternatively, power control processor 208 produces powercontrol messages representing the absolute power of the received forwardlink signal, as is known in the art. The power control processor 208produces preferably several (e.g., sixteen) power control messages inresponse to several power level signals per frame. While the qualitymeasurement circuit 206 and power control processor 208 are generallydescribed herein as separate components, such components can bemonolithically integrated, or the operations performed by suchcomponents can be performed by a single microprocessor.

A mobile transmission system 210 encodes, modulates, amplifies, and upconverts the power control messages, via the duplexer 203 and theantenna 202. In the illustrated embodiment, the mobile transmissionsystem 210 provides the power control message in a predeterminedlocation of an outgoing reverse link frame.

The mobile transmission system 210 also receives reverse link trafficdata, such as voice or general computer data, from the user of themobile station. The mobile transmission system 210 requests a particularservice (including power/rate) from the base station 106 a based on thetraffic data to be transmitted. In particular, the mobile transmissionsystem 210 requests bandwidth allocation appropriate for the particularservice. The base station 106 a then schedules or allocates bandwidth(power/rate) resources based on requests from the mobile station 102 andother users to optimize such resource allocation, given powerconstraints of the system. Thus, effectively managing transmission powerin the system will permit more effective bandwidth use.

The base station 106 a includes a receiving antenna 230 that receivesthe reverse link frames from the mobile station 102. A receiver system232 of the base station 106 a down converts, amplifies, demodulates, anddecodes the reverse link traffic. A backhaul transceiver 233 receivesand forwards to the base station controller 104 reverse link traffic.The receiver system 232 also separates the power control messages fromeach reverse link traffic frame and provides the power control messagesto a power control processor 234.

The power control processor 234 monitors the power control messages andproduces a forward link transmitter power signal to a forward linktransmitter system 236. The forward link transmitter system 236, inresponse thereto, increases, maintains, or decreases the power of theforward link signal. The forward link signal is then transmitted via atransmitting antenna 238. Additionally, the power control processor 234analyzes the quality of the reverse link signal from the mobile station102 and provides appropriate feedback control messages to the forwardlink transmitter system 236. The forward link transmitter system 236, inresponse thereto, transmits the feedback control messages via thetransmitting antenna 238 over the forward link channel to the mobilestation 102. The transmitter system 236 also receives forward linktraffic data from the base station controller 104 via the backhaultransceiver 233. The forward link transmitter system 236 encodes,modulates, and transmits via the antenna 238 the forward link trafficdata.

Unless described otherwise herein, the construction and operation of thevarious blocks and elements shown in FIGS. 1 and 2 and the other figuresare of conventional design and operation. Thus, such blocks or elementsneed not be described in further detail because they will be understoodby those skilled in the relevant art. Any additional description isomitted for brevity and to avoid obscuring the detailed description ofthe invention. Any modifications necessary to the blocks of thecommunication system 100 of FIGS. 1 and 2, or the other systems showntherein can be readily made by one skilled in the relevant art based onthe detailed description provided herein.

The closed-loop power control system for user stations, including themobile station 102 and base station 106 a, dynamically adjusts thetransmit power for each user based on the user's propagation conditionsto yield the same frame error rate (FER) for each user for voiceservices (e.g., a 1% FER). As noted above, many users, however, mayrequest transmission for data services in lieu of voice services, suchas facsimile, e-mail and general computer data, all of which areinsensitive to delay but require a lower FER (or lower bit error rate(BER)). A user may even require video services, which not only require alower FER but are sensitive to delay. The base station 106 a dynamicallyassigns transmission rates based on requests from each user under knowntechniques.

Under one CDMA standard, described in the Telecommunications IndustryAssociation's TIA/EIA-95-A Mobile Stations-Base Station CompatibilityStandard For Dual-Mode Wideband Spread Spectrum Cellular System, eachbase station transmits pilot, sync, paging, and forward traffic channelsto its users. The pilot channel is an unmodulated, direct-sequencespread spectrum signal transmitted continuously by each base station.The pilot channel enables each user to acquire the timing of thechannels transmitted by the base station, and it provides a phasereference for coherent demodulation. The pilot channel also provides ameans for signal strength comparisons between base stations to determinewhen to hand off between base stations (such as when moving betweencells). Recent CDMA modulation techniques have been proposed usingdedicated time multiplexed (“DTMP”) pilot symbols. Under the DTMPapproach, separate pilot symbols are time multiplexed on each user'straffic channel. Each user sequentially de-spreads the pilot symbols(and information symbols). There is also an alternative common codemultiplexed pilot (“CCMP”) approach, where one co-channel is dedicatedto broadcasting a pilot signal. No pilot symbols are multiplexed withdedicated channels, and all users de-spread both the pilot symbols andthe modulated information signals in parallel. Such systems aredescribed in more detail in U.S. Pat. No. 6,310,869, issued Oct. 30,2001, entitled METHOD AND APPARATUS FOR REDUCING AMPLITUDE VARIATIONSAND INTERFERENCE IN COMMUNICATION SIGNALS, SUCH AS WIRELESSCOMMUNICATION SIGNALS EMPLOYING INSERTED PILOT SYMBOLS, assigned to thesame assignee of this invention.

Inter-Frequency Search

Referring next to FIG. 3, shown therein is a diagram of the differenttiming involved in performing a search excursion. While FIG. 3 would beself-explanatory to one of ordinary skill in the relevant art, a briefexplanation is provided. The reference tsearch corresponds to the timerequired to collect the N samples on frequency f2. The total time willbe t_(search) plus the time it takes to process the samples afterreturning to the original frequency f1. The times t_(synth) andt_(settle) correspond to the time required to switch and settle at a newfrequency, respectively. The time period of N_(s)×T_(c) represents thesampling time for N_(samples), and t_(process) represents the time toprocess the samples.

A method for minimizing the search time to another frequency can bedescribed as follows:

First, the mobile station is currently demodulating an original or firstfrequency f1. An inter-frequency hard handoff to a target frequency f2might be required, such as when certain signal quality measurements(e.g., those noted above) fall below predetermined thresholds. Whenreporting such dropping quality to the base station 106 a, the mobilestation 102 is directed by the base station (e.g., via a CandidateFrequency Search Request/Control Message (“CFSCM”)) to perform a searchexcursion to a target frequency f2.

The mobile station tunes to frequency f2 and collects N chip samples (achip being one bit of pseudonoise at, for example, 1024 bps fororthogonally encoded symbols). The samples are stored in a memorybuffer; the mobile station does not perform pilot searches and pilotstrength measurements while on frequency f2. The mobile station tunesback to the original frequency f1, resumes reception of forward link andtransmission of reverse link, and processes the N samples collected onfrequency f2 simultaneously.

The mobile station processes the samples collected on frequency f2 usinga searcher that processes the stored samples while simultaneouslyprocessing the signal received on the original frequency f1. The mobilestation reports to the base station the corresponding pilot strengthmeasurements from frequency f2. One of skill in this technology willrecognize the searcher referred to above and would have the requisiteskill to provide or obtain the same.

The foregoing method is illustrated in FIG. 4 as a routine 400 thatbegins in step 410 where the base station 106 a transmits a frequencychange command to the mobile station 102 under a Candidate FrequencySearch Request Control Message as defined by TIA/EIA-95-B Standardincorporated by reference. In response to this command, the mobilestation 102 tunes to the target frequency f2 under step 420.

In step 430, the mobile station 102 collects signal samples at thetarget frequency f2 and locally stores the samples in the memory buffer207. Under step 440, the mobile station 102 tunes back to the firstfrequency f1 and processes the signal samples stored in the memorybuffer 207 under step 450. Note, steps 440 and 450 can be performedconcurrently.

After the signal samples are processed as described above, the mobilestation 102 under step 460 transmits the signal sample processingresults to the base station 106 a.

Minimizing Impact of Search Excursion on Current Frame

When the mobile station tunes to another frequency f2 to perform aninter-frequency search, forward link symbols transmitted by the basestation during the t_(search) time period cannot be received by themobile station. Similarly, the mobile station does not transmit duringt_(search) and the base station loses reverse link symbols during thet_(search) time period. To minimize the impact of this loss on both thecurrent forward and reverse link frames, the mobile and base stationsincrease the amount of power allocated to the other symbols of theforward-error-correction-encoded and interleaved frame of symbolsimpacted by the search excursion. For the frame to be demodulatedcorrectly, the additional amount of power required for symbols notimpacted by the search excursion is a function of the search excursiontime t_(search), as noted herein.

Forward Link Power Control During Search Visit

To overcome the loss of forward link symbols during the t_(search) timeperiod, the mobile station increases the target E_(b)/N_(o) of theforward link closed-loop fast power control by Δ_(target) dB.

This new target E_(b)/N_(o) is set K power control groups (PCG) beforethe search excursion. The required number K of previous PCGs affectedbefore the search excursion and the required increase in targetE_(b)/N_(o) (Δ_(target)) depends on the duration of the search excursiont_(search); the longer t_(search) is, the larger K. As a result of theincrease in the target E_(b)/N_(o), the forward link power will ramp-upprior to the inter-frequency search.

FIG. 5 illustrates the succession of forward link power levels relatedto an inter-frequency search excursion. Although FIG. 5 isself-explanatory to one of ordinary skill in the relevant art, a briefexplanation is provided. After the search excursion, the mobile station102 resumes demodulation of the forward link symbols of the currentframe. At this stage the mobile station 102 knows the total symbolenergy received in the current frame and can compare this to therequired energy per frame to achieve the target frame error rate. Themobile station 102 can use this metric to increase or decrease thetarget E_(b)/N_(o) for the remaining power control groups of the frame.If the search excursion expands over a frame boundary, the mobilestation 102 may increase its target E_(b)/N_(o) during the next frame tomake up for the lost symbols in the first part of the frame. Detailsregarding closed loop power control can be found, for example, in U.S.Pat. Nos. 6,075,974 and 5,982,760, entitled “METHOD AND APPARATUS FORADJUSTING THRESHOLDS AND MEASUREMENTS OF RECEIVED SIGNALS BYANTICIPATING POWER CONTROL COMMANDS YET TO BE EXECUTED,” and “METHOD ANDAPPARATUS FOR POWER ADAPTATION CONTROL AND CLOSED-LOOP COMMUNICATION,”issued Jun. 13, 2000, and Nov. 9, 1999, all respectively, and assignedto the assignee of this invention.

Reverse Link Power Control During Search Visit

While searching on the target frequency f2, the base station 106 a willlose communication with the mobile station 102 and will not receivesymbols during the t_(search) time period. To overcome the loss of thosesymbols, the mobile station 102 can increase the total transmissionpower on the reverse link by a quantity Δ_(search) dB. The quantityΔ_(search) depends on the duration of the search t_(search) andcorresponds to the additional required symbol energy over the remainderof the frame to overcome the loss of symbols during t_(search) and stillpermit the base station 106 a to demodulate the frame correctly. Thebase station 106 a can inform the mobile station 102 of the maximumtolerable increase Δ_(search) dB in the message directing the mobilestation to perform an inter-frequency search (e.g., in the (“FCSM”)).This value can depend on the maximum tolerable interference currentlydetermined by the base station 106 a.

FIG. 6 illustrates the succession of reverse link power increases duringa search excursion. While FIG. 6 would be self-explanatory to one ofordinary skill in the relevant art, a brief explanation is provided.During the inter-frequency search frame, transmitted with a powerincrease, the base station 106 a will send down commands ordering themobile station 102 to reduce its power. The mobile station 102 simplyignores those down commands until the end of inter-frequency searchframe, as shown in FIG. 6. These up and down commands are represented bythe large dark arrows 602, 604, respectively, in FIG. 6. If the searchexcursion expands over a frame boundary, the mobile station 102 canincrease its total transmit power during the next frame in a fashionsimilar to that noted above to overcome the loss of the initial symbolsof the next frame. Regular power control resumes after the frameboundary, as shown in FIG. 6.

Thus, the method described previously with respect to FIG. 4 can bemodified to ensure uninterrupted communication during a searchexcursion. FIG. 7 shows the steps of the modified method, beginning withstep 710, where the base station 106 a transmits the frequency changecommand (FCSM) to the mobile station 102.

Before the mobile station 102 tunes to the target frequency, the targetE_(b)/N_(o) of the forward link closed-loop fast power control isincreased from a first level to a second level as described above. Themobile station 102 increases the total transmission power on the reverselink by a quantity Δ_(search) dB, as also described above andillustrated in step 720.

The mobile station then tunes to the target frequency and collectstarget frequency signal samples, such as chip sample data, and storesthe signal samples in the memory 207, under steps 730-740.

In step 750, the mobile station 102 tunes back to the first frequencywhen the collection of signal samples is complete. The mobile station102 processes the signal samples in the memory buffer and resumescommunication with the base station 106 a at the first frequency f1. Inresuming communications, the mobile station 102 adjusts the targetE_(b)/N_(o) of the remaining power control groups in the frame, and thenreduces the target E_(b)/N_(o) by Δ_(target) and the reverse link totaltransmission power resumes regular control, as illustrated in step 760.

Finally, under 780, the signal sample processing results, such as at thepilot strength measurements, are transmitted to the base station.

The base station 106 a and the mobile station 102 can be configured toaccomplish the foregoing process. Source code to accomplish theforegoing can be readily generated by those of ordinary skill in thistechnology based on the detailed description provided herein.

While a preferred embodiment of the invention has been illustrated anddescribed above, it is to be understood that various changes may be madetherein without departing from the spirit and scope of the invention.For example, the mobile station 102 can use the state of its long codemask to select a starting position within a frame to perform theinter-frequency search. The mobile station 102 can select arandomization period such that the inter-frequency search wouldtypically not expand over a frame. Randomizing the search excursionposition between different mobile stations will reduce the reverse linkinterference and will decrease the total power requirement on theforward link. Consequently, the invention is to be limited only by thescope of the claims that follow.

Although specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various equivalentmodifications can be made without departing from the scope of theinvention, as will be recognized by those skilled in the relevant art.For example, embodiments are generally shown and described as beingimplemented in software and performed by a processor. Such software canbe stored on any suitable computer-readable medium, such as microcodestored in a semiconductor chip, computer-readable disk, or downloadedand stored from a server. The invention could equally be implemented inhardware, such as by a DSP or ASIC.

The teachings provided herein of the invention can be applied to othercommunications systems, not necessarily the illustrated communicationsystem described above. For example, while the invention has beengenerally described above as being employed in the CDMA communicationsystem 100, the invention is equally applicable to other digital oranalog cellular communication systems. The invention can be modified toemploy aspects of the systems, circuits, and concepts of the variouspatents and standards described above, all of which are incorporated byreference.

These and other changes can be made to the invention in light of theabove detailed description. In general, in the following claims, theterms should not be construed to limit the invention to the specificembodiments disclosed in the specification and the claims. Accordingly,the invention is not limited by the disclosure, but instead its scope isto be determined entirely by the following claims.

1. An apparatus comprising: a quality measurement circuit; and a powercontrol processor configured to tune to a first frequency during aninitial portion of a first frame, to tune to a second frequency during aperiod that begins during the first frame and continues through aninitial portion of a second frame, wherein the second frame followsimmediately after the first frame, to direct the quality measurementcircuit to measure at least one signal attribute on the second frequencyduring the period, and to tune the receiver on the first frequencyduring a remaining portion of the second frame; wherein said powercontrol processor is further configured to increase a target over atleast a portion of at least one of the first and second frames.
 2. Theapparatus of claim 1 wherein the power control processor is furtherconfigured to direct a mobile transmission module to increase an amountof power allocated to symbols transmitted on the first frequency duringthe initial portion of the first frame.
 3. The apparatus of claim 1wherein the power control processor is further configured to direct amobile transmission module to increase an amount of power allocated tosymbols transmitted on the first frequency during the remaining portionof the second frame.
 4. The apparatus of claim 1 wherein the powercontrol processor is further configured to direct a mobile transmissionmodule to increase an amount of power allocated to symbols transmittedon the first frequency during the initial portion of the first frame andon the first frequency during the remaining portion of the second frame.5. The apparatus of claim 1 wherein the power control processor isfurther configured to generate a report indicative of a measurement ofthe at least one signal attribute.
 6. The apparatus of claim 5 whereinthe power control processor is further configured to provide the reportto a mobile transmission module to be wirelessly transmitted on thefirst frequency.
 7. A method, comprising: tuning to a first frequencyduring an initial portion of a first frame; tuning to a second frequencyduring a period that begins during the first frame and continues throughan initial portion of a second frame, wherein the second frame followsimmediately after the first frame; measuring at least one signalattribute on the second frequency during the period; and tuning to thefirst frequency during a remaining portion of the second frame, whereina target is increased over at least a portion of at least one of thefirst and second frames.
 8. The method of claim 7 further comprisingincreasing an amount of power allocated to symbols transmitted on thefirst frequency during the initial portion of the first frame.
 9. Themethod of claim 7 further comprising increasing an amount of powerallocated to symbols transmitted on the first frequency during theremaining portion of the second frame.
 10. The method of claim 7 furthercomprising: increasing an amount of power allocated to symbolstransmitted on the first frequency during the initial portion of thefirst frame; and increasing an amount of power allocated to symbolstransmitted on the first frequency during the remaining portion of thesecond frame.
 11. The method of claim 7 further comprising generating areport indicative of a measurement of the at least one signal attribute.12. The method of claim 11 further comprising transmitting the report onthe first frequency.
 13. An apparatus, comprising: means for tuning to afirst frequency during an initial portion of a first frame; means fortuning to a second frequency during a period that begins during thefirst frame and continues through an initial portion of a second frame,wherein the second frame follows immediately after the first frame;means for measuring at least one signal attribute on the secondfrequency during the period; and means for tuning to the first frequencyduring a remaining portion of the second frame, wherein a target isincreased over at least a portion of at least one of the first andsecond frames.
 14. The apparatus of claim 13 further comprising meansfor increasing an amount of power allocated to symbols transmitted onthe first frequency during the initial portion of the first frame. 15.The apparatus of claim 13 further comprising means for increasing anamount of power allocated to symbols transmitted on the first frequencyduring the remaining portion of the second frame.
 16. The apparatus ofclaim 13 further comprising: means for increasing an amount of powerallocated to symbols transmitted on the first frequency during theinitial portion of the first frame; and means for increasing an amountof power allocated to symbols transmitted on the first frequency duringthe remaining portion of the second frame.
 17. The apparatus of claim 13further comprising means for generating a report indicative of ameasurement of the at least one signal attribute.
 18. The apparatus ofclaim 17 further comprising means for transmitting the report on thefirst frequency.